JP7315953B2 - Water spray method and water spray system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water spraying method and a water spraying system, and more particularly to a water spraying method and a water spraying system for spraying pure water or ultrapure water.

A method of spraying water from nozzles is known for cooling and humidifying spaces in factories and facilities. In this case, if tap water is used as the water to be sprayed from the nozzle, impurities such as salts contained in the water may adhere as white powder to the walls, floors, and equipment of the room, causing a problem. In order to avoid such problems, it is conceivable to use pure water or ultrapure water from which salts and impurities are highly removed as the water to be sprayed from the nozzle. However, when pure water or ultrapure water is sprayed from a nozzle, due to the low electrical conductivity of pure water or ultrapure water, the water is charged during the process of atomization, and water droplets adhere to the nozzle body and peripheral equipment. However, problems such as dripping of water occur. As a method for solving such a problem, in Patent Document 1, carbon dioxide gas is bubbled into pure water to dissolve the carbon dioxide gas to increase electrical conductivity, and thus pure water with increased electrical conductivity is disclosed. from a nozzle is disclosed.

WO2017/159630

According to the method described in Patent Document 1, the electrical conductivity of pure water can be increased by supplying carbon dioxide gas to the pure water. In addition to this, equipment for bubbling carbon dioxide gas into pure water to dissolve it tends to be expensive. The present invention has been made in view of the above circumstances, and it is possible to easily increase the electrical conductivity of pure water or ultrapure water. To provide a spraying method and a spraying system.

The water spraying method of the present invention that can solve the above problems includes a first spraying step of spraying pure water or ultrapure water into a tank, and pure water whose electric conductivity is increased by the first spraying step. or a second spraying step of spraying ultrapure water out of the tank. According to the water spraying method of the present invention, by spraying pure water or ultrapure water in the tank in the first spraying step, carbon dioxide in the air dissolves in the atomized pure water or ultrapure water, The electric conductivity of pure water or ultrapure water can be easily increased. Then, by spraying the pure water or ultrapure water whose electric conductivity is increased in this way outside the tank in the second spraying process, the charging of the sprayed water is suppressed, and the water dripping from the nozzle is suppressed. can be effectively sprayed with pure water or ultrapure water.

In the first spraying step, it is preferable to spray pure water or ultrapure water with water droplets having an average particle size of 100 μm or more and 1000 μm or less. The electric conductivity of pure water or ultrapure water sprayed in the first spraying step is preferably less than 1.0 μS/cm.

In the second spraying step, it is preferable to spray pure water or ultrapure water with increased electrical conductivity as water droplets having an average particle size of 5 μm or more and less than 100 μm. In the second spraying step, it is preferable to spray pure water or ultrapure water with increased electrical conductivity while blowing air from behind, so that in the second spraying step, water drips from the nozzle more easily. less likely to occur.

The present invention also includes a tank, a first nozzle for spraying pure water or ultrapure water into the tank, and a discharge port of the tank, and discharging the pure water or ultrapure water sprayed into the tank to the outside of the tank. A water spray system is also provided having a spraying second nozzle. According to the water spray system of the present invention, by spraying pure water or ultrapure water from the first nozzle, carbon dioxide in the air dissolves in the sprayed pure water or ultrapure water, resulting in pure water or ultrapure water. The electric conductivity of water can be simply increased. By spraying the pure water or ultrapure water with increased electric conductivity from the second nozzle to the outside of the tank, the sprayed water can be suppressed from being charged, and water dripping from the nozzle can be prevented. Pure water or ultrapure water can be suitably sprayed.

The first nozzle preferably sprays water droplets having an average particle size of 100 µm or more and 1000 µm or less. Moreover, it is preferable that the first nozzle is provided on the side surface of the tank. The electric conductivity of pure water or ultrapure water sprayed from the first nozzle is preferably less than 1.0 μS/cm.

The second nozzle preferably sprays water droplets having an average particle size of 5 μm or more and less than 100 μm. It is also preferable that the second nozzle is provided with a blower fan behind it.

According to the water spraying method and water spraying system of the present invention, pure water or ultrapure water is once sprayed into the tank, and carbon dioxide in the air dissolves in the sprayed pure water or ultrapure water to produce pure water. The electric conductivity of water or ultrapure water can be easily increased. By spraying pure water or ultrapure water with increased electrical conductivity to the outside of the tank, charging of the sprayed water is suppressed, water dripping from the nozzle is prevented, and the water is kept pure. Water or ultrapure water can preferably be sprayed.

1 shows a configuration example of a water spray system of the present invention.

The water spraying method of the present invention includes a first spraying step of spraying pure water or ultrapure water into the tank, and spraying the pure water or ultrapure water whose electrical conductivity has been increased by the first spraying step out of the tank. and a second spraying step. According to the present invention, by spraying pure water or ultrapure water in a tank, carbon dioxide in the air dissolves in the atomized pure water or ultrapure water, so that electrical conductivity can be increased. By spraying pure water or ultra-pure water in the tank, even if the pure water or ultra-pure water is charged and drips from the nozzle, the dropped water will accumulate in the tank, so there is no problem. . By spraying pure water or ultrapure water with increased electrical conductivity to the outside of the tank, charging of the sprayed water is suppressed, water dripping from the nozzle is prevented, and the water is kept pure. Water or ultrapure water can preferably be sprayed.

The pure water or ultrapure water sprayed in the first spraying step is highly free of impurities such as salts and residual chlorine, and has an electric conductivity of less than 1.0 μS/cm, for example. The electrical conductivity of pure or ultrapure water may be even lower, and may be 0.7 S/cm or less, 0.5 μS/cm or less, 0.3 μS/cm or less, or 0.2 μS/cm or less. .

Deionized water or distilled water can be used as pure water or ultrapure water. Deionized water is water obtained by ion exchange treatment such as ion exchange resin, ion exchange membrane, and electrically regenerative ion exchange device (EDI). ions other than oxide ions) are highly removed. Distilled water is water obtained by a distillation process, which again results in water from which impurities are highly removed. These ion exchange treatment and distillation treatment may be performed in combination with reverse osmosis membrane treatment and adsorption treatment (for example, adsorption treatment with activated carbon). Moreover, ions in water may be removed to a high degree by combining reverse osmosis membrane treatments in multiple stages to obtain pure water or ultrapure water.

The shape and size of the tank are not particularly limited. The shape of the tank includes, for example, a substantially cylindrical shape, a substantially rectangular parallelepiped shape, and the like. The tank may be either closed or open, movable or non-movable. The tank may be, for example, a water tank installed on the ground or in a building.

The size of the tank depends on the spray amount of the nozzle that sprays inside the tank (hereinafter referred to as the "first nozzle") and the nozzle that sprays the pure water or ultrapure water in the tank outside the tank (hereinafter referred to as the "second nozzle"). It may be appropriately set according to the spray amount of the nozzle (referred to as "2 nozzles"). For example, when the tank capacity (the specified capacity of the tank) is X (L), the spray amount from the first nozzle is A (L/min), and the spray amount from the second nozzle is B (L/min) , the ratio X/A and the ratio X/B are each preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and preferably 150 or less, more preferably 100 or less, and even more preferably 50 or less.

The tank should hold a predetermined amount or more of the pure water or ultrapure water sprayed from the first nozzle in order to prevent air entrainment of the pump that sends the pure water or ultrapure water stored in the tank to the second nozzle. is preferred. For example, the tank preferably holds pure water or ultrapure water in an amount of 1/10 or more, more preferably 2/10 or more, and even more preferably 3/10 or more of the specified capacity of the tank. Pure water or ultrapure water may be held in the tank up to the specified capacity of the tank. Therefore, the tank preferably holds pure water or ultrapure water in an amount of 9/10 or less of the specified capacity of the tank, more preferably 8/10 or less, and 7/10 More preferred are:

The tank is provided with a first nozzle for spraying pure water or ultrapure water. As the first nozzle, a one-fluid nozzle that injects only water or a two-fluid nozzle that injects water and air can be used. It is preferable to use a one-fluid nozzle.

The first nozzle is preferably one capable of spraying fine water droplets to a certain extent, so that carbon dioxide in the air can be efficiently dissolved in the pure water or ultrapure water. The first nozzle preferably sprays water droplets having an average particle size of 1000 µm or less, more preferably 800 µm or less, and even more preferably 600 µm or less. That is, in the first spraying step, it is preferable to spray pure water or ultrapure water as water droplets having an average particle size of 1000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less.

The lower limit of the average particle size of water sprayed from the first nozzle is not particularly limited, and may be, for example, 10 µm or more, or 50 µm or more. If the average particle size is too small, it will take time for the water sprayed from the first nozzle to accumulate in the tank, and it will be necessary to supply water at a higher pressure, so the equipment will have to be highly specified. tend to Therefore, the first nozzle preferably sprays water droplets having an average particle size of 100 μm or more, more preferably 120 μm or more, and even more preferably 150 μm or more. That is, in the first spraying step, it is preferable to spray pure water or ultrapure water as water droplets having an average particle size of 100 μm or more, more preferably 120 μm or more, further preferably 150 μm or more.

The average particle size of water droplets described here is obtained by measuring the particle size distribution of water droplets at a point 30 cm from the tip of the nozzle using a phase Doppler particle analyzer for water sprayed from the nozzle. means the Sauter mean particle size of The first nozzle is removed from the tank, water is sprayed under the same conditions as spraying into the tank, and the average particle size at this time is measured. The average particle size of the second nozzle, which will be described later, is also measured in the same manner.

In the first spraying step, it is convenient to spray pure water or ultrapure water into the air. For example, carbon dioxide gas may be supplied into the tank so that the concentration of carbon dioxide in the tank is higher than the concentration of carbon dioxide in the air. In this case, carbon dioxide can be dissolved in pure water or ultrapure water more efficiently.

The direction of spraying water from the first nozzle is not particularly limited, and it may be sprayed in a horizontal direction, may be sprayed downward, may be sprayed upward, or may be sprayed in an oblique direction. . It is preferable to spray the water from the first nozzle at a wide angle to some extent, for example, to spray the water in a fan shape, a conical shape, or an empty conical shape. The spray angle of water from the first nozzle is, for example, preferably 30° or more, more preferably 45° or more, still more preferably 60° or more, preferably 150° or less, and more preferably 135° or less.

The first nozzle may be provided on the side surface or top surface of the tank, or may be provided inside the tank. From the point of view of increasing the contact efficiency of the pure water or ultrapure water sprayed in the tank with carbon dioxide in the air, regardless of the amount of pure water or ultrapure water stored in the tank, the spray of the first nozzle It is preferable that the distance is ensured. From this point of view, the first nozzle is preferably provided on the side surface of the tank, so that at least the horizontal length inside the tank can be secured as the spatial distance in front of the first nozzle. The distance from the tip of the first nozzle to the tank wall surface is, for example, preferably 8 cm or longer, more preferably 10 cm or longer, and even more preferably 12 cm or longer.

The spray pressure of the first nozzle is, for example, preferably 0.05 MPa or higher, more preferably 0.08 MPa or higher, and 0.1 MPa or higher in terms of promoting atomization of pure water or ultrapure water sprayed from the first nozzle. is more preferred. On the other hand, even if the spray pressure of the first nozzle is excessively increased, the effect of carbon dioxide dissolving in the pure water or ultrapure water sprayed from the first nozzle is saturated, and the equipment specifications for pumps and tanks become higher. Therefore, the spray pressure of the first nozzle is preferably 1.0 MPa or less, more preferably 0.8 MPa or less, and even more preferably 0.5 MPa or less. The spray pressure of the nozzle corresponds to the water supply pressure to the nozzle.

The tank preferably stores pure water or ultrapure water sprayed from the first nozzle. In addition, the first nozzle is preferably provided above the surface of pure water or ultrapure water in the tank. As a result, the water surface of the pure water or ultrapure water stored in the tank is disturbed by the water sprayed from the first nozzle, and the pure water or ultrapure water remains even when the pure water or ultrapure water is stored in the tank. carbon dioxide gradually dissolves in For example, it is sufficient for the first nozzle to be above the pure water or ultrapure water surface by 3 cm or more, and it may be provided closer to the water surface than that.

The pure water or ultrapure water sprayed into the tank from the first nozzle is preferably held in the tank for a certain amount of time. Therefore, the water spraying method of the present invention preferably further includes a step (retention step) of retaining the pure water or ultrapure water, the electric conductivity of which has been increased by the first spraying step, in the tank. Due to the retention step, carbon dioxide is further dissolved in the pure water or ultrapure water stored in the tank, making it possible to increase the electric conductivity of the pure water or ultrapure water sprayed from the second nozzle.

In the residence step, the residence time of the pure water or ultrapure water in the tank is preferably 3 minutes or longer, more preferably 5 minutes or longer, and even more preferably 8 minutes or longer. The upper limit of the retention time of the pure water or ultrapure water in the first tank is not particularly limited. Since the capacity becomes excessive, the retention time is preferably 60 minutes or less, more preferably 45 minutes or less, and even more preferably 30 minutes or less. The retention time of pure water or ultrapure water in the tank is calculated by dividing the amount (L) of pure water or ultrapure water stored in the tank by the amount of spray from the second nozzle (L/min). be able to. In a steady state, it is preferable that the amount of spray from the first nozzle and the amount of spray from the second nozzle are approximately the same, so that the storage amount in the tank can be maintained substantially constant.

The tank is provided with an outlet for extracting the pure water or ultrapure water sprayed from the first nozzle to the outside of the tank. The outlet is preferably provided at the bottom of the tank. Preferably, the outlet is provided further downward. Preferably, the second nozzle is provided in communication with this outlet, and pure water or ultrapure water drawn out from the tank is supplied to the second nozzle by a pump. A submersible pump may be installed in the tank, and the pure water or ultrapure water stored in the tank may be supplied to the second nozzle by the submersible pump. In this case, the suction port of the submersible pump becomes the discharge port of the tank.

Pure water or ultrapure water sprayed into the tank is sprayed out of the tank from the second nozzle, and a second spraying step is performed. In the second spraying step, pure water or ultrapure water whose electrical conductivity has been increased by the first spraying step (or further the retention step) is sprayed out of the tank. By spraying pure water or ultrapure water with increased electrical conductivity from the second nozzle, the water sprayed from the second nozzle is suppressed from being charged, and the water from the nozzle body of the second nozzle and peripheral equipment Pure water or ultrapure water can be suitably sprayed while preventing dripping.

The electrical conductivity of the pure water or ultrapure water sprayed from the second nozzle is higher than the electrical conductivity of the pure water or ultrapure water sprayed from the first nozzle. /cm or more, more preferably 0.5 μS/cm or more, and even more preferably 0.7 μS/cm or more. The electrical conductivity of the pure water or ultrapure water sprayed from the second nozzle is not particularly limited as long as it is higher than the electrical conductivity of the pure water or ultrapure water sprayed from the first nozzle. cm or more is preferable, 0.7 μS/cm or more is more preferable, and 0.9 μS/cm or more is even more preferable.

As the second nozzle, a one-fluid nozzle that injects only water or a two-fluid nozzle that injects water and air can be used. It is preferred to use a nozzle. It is also preferable to install a blower fan behind the second nozzle and spray water from the second nozzle while blowing air from behind. In this case, when pure water or ultrapure water is sprayed from the second nozzle, dripping of water from the second nozzle is less likely to occur.

Although the average particle size of the water sprayed from the second nozzle is not particularly limited, the average particle size of the water sprayed from the second nozzle is is preferably smaller than the average particle size of That is, the smaller the average particle size of the water sprayed from the second nozzle, the more easily electrification occurs when the pure water or ultrapure water is sprayed and atomized. Even if pure water or ultrapure water is sprayed from the second nozzle under the condition that charging causes problems such as dripping of water, such problems are less likely to occur.

The average particle size of the water sprayed from the second nozzle is, for example, preferably less than 100 μm, more preferably 60 μm or less, even more preferably 30 μm or less. That is, the second nozzle preferably sprays water droplets having an average particle size of less than 100 μm, more preferably 60 μm or less, and even more preferably 30 μm or less. Further, in the second spraying step, pure water or ultrapure water whose electrical conductivity has been increased in the first spraying step or in the retention step is preferably sprayed with water droplets having an average particle size of less than 100 μm, and the average particle size is more preferably 60 μm or less, more preferably 30 μm or less. The lower limit of the average particle size of the water sprayed from the second nozzle is not particularly limited, and may be, for example, 5 µm or more, 10 µm or more, or 15 µm or more. For the second nozzle, for example, a nozzle that sprays dry mist, that is, a nozzle that can spray fine mist to the extent that it does not feel wet when touched can be used.

The installation location and spray direction of the second nozzle are not particularly limited, and may be appropriately set according to the purpose of use of the second nozzle and the environment in which the second nozzle is installed. The second nozzle can be installed, for example, for purposes such as humidification, cooling, static electricity prevention, and air cleaning.

The spray pressure of the second nozzle may be appropriately set according to the particle size and spray amount of water sprayed from the second nozzle. As described above, the smaller the average particle size of the water sprayed from the second nozzle, the more pronounced the effect of the present invention. Therefore, the spray pressure of the second nozzle is at least higher than the spray pressure of the first nozzle. Large is preferred. The spray pressure of the second nozzle is, for example, preferably 3.0 MPa or higher, more preferably 4.0 MPa or higher, and even more preferably 5.0 MPa or higher. On the other hand, the spray pressure of the second nozzle is preferably less than 10.0 MPa, more preferably 8.0 MPa or less, from the viewpoint of suppressing the equipment specifications of the second nozzle and its peripheral equipment (for example, a pump that sends water to the second nozzle). .

Next, a configuration example of the water spray system of the present invention will be described with reference to FIG. It should be noted that the present invention is not limited to the embodiments shown in the drawings.

The water spray system of the present invention communicates with a tank 1 , a first nozzle 2 for spraying pure water or ultrapure water 11 into the tank 1 , and an outlet 3 of the tank 1 . and a second nozzle 4 for spraying water or ultrapure water 12 out of the tank 1 . By spraying pure water or ultrapure water 11 from the first nozzle 2, carbon dioxide in the air dissolves in the pure water or ultrapure water 11, and pure water or ultrapure water 12 with increased electric conductivity is produced. can get.

The first nozzle 2 is preferably provided on the side surface of the tank 1, and the tip of the first nozzle 2 is preferably oriented substantially horizontally. The first nozzle 2 is preferably a nozzle that sprays water droplets having an average particle diameter of 100 μm to 1000 μm, for example.

The tank 1 preferably stores pure water or ultrapure water 11 sprayed from the first nozzle 2 . The pure water or ultrapure water 12 stored in the tank 1 is sprayed with the pure water or ultrapure water 11 sprayed from the first nozzle 2 so that the water surface is disturbed and stored in the tank 1. During this time, more carbon dioxide dissolves, increasing electrical conductivity. It is preferable to adjust the amount of pure water or ultrapure water 12 stored in the tank 1 so that the retention time of the pure water or ultrapure water 12 in the tank 1 is 3 minutes or more.

Pure water or ultrapure water 12 stored in the tank 1 is sent to the second nozzle 4 by a pump and sprayed from the second nozzle 4 . The second nozzle 4 is preferably a nozzle that sprays water droplets having an average particle size of 5 μm or more and less than 100 μm, and for example, a nozzle that can spray fine mist that does not feel wet when touched is preferable. Since the pure water or ultrapure water 12 sprayed from the second nozzle 4 has an increased electric conductivity, even if the pure water or ultrapure water 12 is sprayed from the second nozzle in fine mist, Dripping of water due to static electricity is less likely to occur.

EXAMPLES The present invention will be described in more detail below by showing Examples, but the scope of the present invention is not limited to these.

(1) Change in electrical conductivity of pure water depending on the type of first nozzle and spray conditions (1-1) Experimental method One-fluid nozzle or hose sprayed or supplied pure water and received it in a beaker, before spraying and spraying ( or supplied) was measured for electrical conductivity of pure water immediately after. Deionized water obtained by treating tap water with a reverse osmosis membrane and then with an ion exchange membrane was used as pure water sprayed from a nozzle or supplied from a hose. As a control, the electrical conductivity of pure water before being sprayed from a nozzle or supplied from a hose was measured.

(1-2) Experimental results (1-2-1) Experiment 1: Examination of nozzle type Pure water is sprayed or supplied from a nozzle or hose, and pure water is electrically conducted before spraying and immediately after spraying (or supplying). rate was measured. The nozzles consist of a one-fluid nozzle (manufactured by Ikeuchi Co., Ltd., VVP series) that sprays in a fan-shaped spray pattern, a one-fluid nozzle (manufactured by Ikeuchi Co., Ltd., BBXP series) that sprays in a conical spray pattern, and an empty conical spray pattern. Three types of single-fluid nozzles (K series, manufactured by Ikeuchi Co., Ltd.) were examined. The average particle size of the water sprayed from each nozzle was in the range of 230 μm to 440 μm for the VVP series nozzles, 230 μm to 450 μm for the BBXP series nozzles, and 280 μm to 530 μm for the K series nozzles.

The results are shown in Table 1. When the pure water was supplied through a hose, the electric conductivity of the pure water only increased from 0.10 μS/cm to 0.20 μS/cm. When sprayed, the electric conductivity of pure water increased from 0.50 μS/cm to 0.66 μS/cm immediately after spraying. By spraying pure water from a nozzle, carbon dioxide in the air dissolves in the pure water, and the electric conductivity can be efficiently increased.

(1-2-2) Experiment 2: Examination of spray pressure and spray amount Pure water was sprayed from a single-fluid nozzle (manufactured by Ikeuchi Co., Ltd., VVP series), and the electrical conductivity of pure water before and after spraying was measured. . Changes in electrical conductivity of pure water before and after spraying were investigated when the supply pressure (spray pressure) and supply amount (spray amount) of water to the nozzle were changed. The nozzle used was of a specification suitable for the supply pressure and amount of water. Table 2 shows the results. There was almost no difference in electrical conductivity.

(2) Change in electrical conductivity of pure water due to spraying of the first nozzle into the tank (2-1) Experimental method Pure water was sprayed from a single-fluid nozzle into a roughly rectangular parallelepiped tank with a capacity of 50 L, before and after spraying. of pure water was measured. Deionized water obtained by treating tap water with a reverse osmosis membrane and then with an ion exchange membrane was used as the pure water sprayed from the nozzle. Pure water was sprayed into the tank so that a predetermined amount (basically 15 L to 20 L) of pure water was always held in the tank, and the pure water accumulated in the tank was drawn out as appropriate. A conductivity meter was installed in the tank, and the conductivity was measured when a predetermined amount of pure water sprayed from the nozzle accumulated in the tank. Also, as a control, the electric conductivity of pure water before being sprayed into the tank was measured. In the experiment, the type of nozzle, nozzle installation position, spray amount, spray pressure, spray time, etc. were changed, and the electric conductivity of the pure water stored in the tank was measured under each condition.

(2-2) Experimental results (2-2-1) Experiment 3: Change in electrical conductivity of pure water after spraying A one-fluid nozzle (manufactured by Ikeuchi Co., Ltd., VVP series) was placed in the tank so that the tip was oriented horizontally. The pure water was sprayed from the nozzle into the tank, and the electric conductivity of the pure water stored in the tank was measured 5 minutes and 20 minutes after the spraying. The results are shown in Table 3. When the nozzle was sprayed inside the tank, the carbon dioxide in the air dissolved while the sprayed mist was falling, and the electric conductivity of the pure water accumulated in the tank gradually increased. and increased to 0.95 μS/cm 20 minutes after spraying.

(2-2-2) Experiment 4: Examination of installation conditions for nozzles installed in the horizontal direction Install a one-fluid nozzle (manufactured by Ikeuchi Co., Ltd., VVP series) on the wall of the tank or inside the tank so that the tip faces in the horizontal direction. Then, pure water was sprayed from the nozzle into the tank, and the electric conductivity of the pure water before and after spraying was measured. The installation position of the nozzle is changed so that the distance from the tip of the nozzle to the opposing tank wall surface, that is, the distance of the space in front of the nozzle is 340 mm, 240 mm or 140 mm. The installation positions of the nozzles were changed so that the diameter was 30 mm, 60 mm, 130 mm, or 230 mm, and the electrical conductivity of the pure water sprayed from the nozzles at each installation position and accumulated in the tank was measured.

The results are shown in Table 4. The electrical conductivity of the pure water sprayed from the nozzle and accumulated in the tank tends to increase as the distance in front of the nozzle increases and as the height of the nozzle from the water surface increases. However, the difference in electrical conductivity between them was small.

(2-2-3) Experiment 5: Examination of installation conditions for nozzles installed vertically downward One-fluid nozzles (manufactured by Ikeuchi Co., Ltd., VVP series) were installed in the tank so that the tip faced vertically downward, Pure water was sprayed into the tank from a nozzle, and the electrical conductivity of pure water before and after spraying was measured. The installation position of the nozzle is changed so that the height from the water surface in the tank to the tip of the nozzle is 37 mm, 153 mm, 230 mm, or 310 mm. Conductivity was measured.

The results are shown in Table 5. The higher the height of the nozzle from the water surface, the higher the electrical conductivity of the pure water sprayed from the nozzle and stored in the tank. was small. In addition, compared with the case where the nozzle was installed so that the tip of the nozzle was oriented in the horizontal direction (Experiment 4), the electrical conductivity tended to decrease slightly.

(3) Influence of electrical conductivity in spraying pure water from the second nozzle (3-1) Experimental method A plurality of pure waters with different electrical conductivities were sprayed from the nozzle, and the state of adhesion of water to the tip of the nozzle was confirmed. . As the nozzle, a one-fluid nozzle (AU Nozzle 2.4, manufactured by Ikeuchi Co., Ltd.) or a one-fluid nozzle atomizer (LE-2.4, manufactured by Ikeuchi Co., Ltd.) equipped with a blower fan behind it was used. Water droplets having an average particle diameter of 10 μm to 30 μm were sprayed from the nozzle, and the supply pressure (spray pressure) of water to the nozzle was 6.0 MPa, and the supply amount (spray amount) was 2.4 L/hr.

(3-2) Experimental Results When pure water was sprayed using a one-fluid nozzle without a blower fan, a large amount of water adhered to the nozzle when the electric conductivity of the pure water to be sprayed was 0.15 μS/cm. On the other hand, when the electrical conductivity of the pure water to be sprayed is 0.5 μS/cm, a small amount of water adheres to the nozzle, and when the electrical conductivity is 0.9 μS/cm, a very small amount of water adheres to the nozzle. Thus, no water adhered to the nozzle when the electrical conductivity was 1.2 μS/cm. When pure water was sprayed using a one-fluid nozzle equipped with a blower fan, no water adhered to the nozzle even when the electric conductivity of the pure water to be sprayed was 0.5 μS/cm.

1: tank 2: first nozzle 3: outlet 4: second nozzle 11, 12: pure water or ultrapure water

Claims (11)

a first spraying step of spraying pure water or ultrapure water from a first nozzle into the air in the tank;
Carbon dioxide in the air is dissolved in the first spraying step to increase electrical conductivity , and the pure water or ultrapure water stored in the tank is placed below the water surface of the pure water or ultrapure water. and a second spraying step of spraying water out of the tank from a second nozzle communicating with an outlet of the tank . The water spraying method according to claim 1, wherein in the first spraying step, the pure water or ultrapure water is sprayed with water droplets having an average particle size of 100 µm or more and 1000 µm or less. The water spraying method according to claim 1 or 2, wherein in the second spraying step, the pure water or ultrapure water with the increased electrical conductivity is sprayed with water droplets having an average particle size of 5 µm or more and less than 100 µm. The water spraying method according to any one of claims 1 to 3, wherein the electric conductivity of the pure water or ultrapure water sprayed in the first spraying step is less than 1.0 µS/cm. The water spraying method according to any one of claims 1 to 4, wherein in the second spraying step, the pure water or ultrapure water with the increased electrical conductivity is sprayed while blowing air from behind. a tank;
a first nozzle for spraying pure water or ultrapure water into the air in the tank;
a second nozzle that communicates with the outlet of the tank and sprays the pure water or ultrapure water sprayed into the tank and accumulated in the tank to the outside of the tank ;
The pure water or ultrapure water stored in the tank is sprayed from the first nozzle into the tank, thereby dissolving carbon dioxide in the air and increasing electrical conductivity,
A water spray system , wherein a discharge port of the tank is positioned below a water surface of the pure water or ultrapure water stored in the tank. The water spray system according to claim 6, wherein the first nozzle sprays water droplets having an average particle size of 100 µm or more and 1000 µm or less. The water spray system according to claim 6 or 7, wherein the second nozzle sprays water droplets having an average particle size of 5 µm or more and less than 100 µm. The water spray system according to any one of claims 6 to 8, wherein the first nozzle is provided on the side surface of the tank. The water spray system according to any one of claims 6 to 9, wherein the electric conductivity of pure water or ultrapure water sprayed from the first nozzle is less than 1.0 µS/cm. The water spray system according to any one of claims 6 to 10, wherein the second nozzle is provided with a blower fan behind it.

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